La Silla Observatory - Science Operation Department

Delegated Service Observations during a Visitor Mode Run

1- Introduction

1.1- Purpose and scope

This policy clarifies the modality of Delegated Service Mode observations scheduled during a Visitor Mode program.

Due to the special nature of HARPS observations (often devoted to
monitoring), it is frequent to have such a short DSM run (of a few
hours) hosted during a long visitor run. This policy is of direct
application to such cases.

It should be noted that a different policy [1] considers the Target of
Opportunity observations over-riding a visitor mode program.

2- Scheduling of a DSM program during a VM run

2.1- Advance Notice and preparation

The PI of the DSM run will submit a detailed Phase II preparation
package, including OBs and README file, according to the Phase II
instructions valid for the considered period [2].

The PI of a VM run affected by a DSM program will have to be notified
in advance (before the arrival of the observer at La Silla) of the
duration of that DSM program, and of its approximative splitting (e.g.
30min per night, 3x 1h, etc..).

2.2 Scheduling

Before the beginning of the run, the VM run observer and his support
astronomer will decide together of the scheduling of the DSM
observations. This has to be done taking into account the scheduling
requirements of the DSM program described in the Phase II, and
minimizing the impact on the VM run. This schedule should be fairly
detailed, defining a window of about 1/2h for the beginning each DSM OB.

The idea is to lock the schedule in advance so that weather losses can
be allocated to one program or the other without discussion on which
loses the time. The fairness of the system relies on the random aspect
of the weather and technical losses.

2.3 Weather and technical losses

The VM Observer commits to comply to the agreed upon schedule, no
matter what the actual weather conditions turn out to be. Similarly,
technical time losses will not affect that schedule.

For instance, if the conditions are too bad for the VM program to be
executed, and suddenly improve at the beginning of a DSM time slot, the
DSM program will be executed. Alternatively, if the weather is bad
during a DSM time slot, that slot is lost to the DSM program.

A possible exception to this rule is the case of wind pointing limit.
If the DSM program cannot be executed during one of the time slot
because of wind pointing restrictions, the VM program can proceed (and
the DSM loses the time). Alternatively, if the VM program cannot be
performed due to wind pointing restrictions, the DSM could be executed.